1. Field of the Invention
The present invention relates to a lens joint structure for frameless spectacles, particularly appropriate both for connecting a temple to each lens and for connecting a bridge to the lenses arranged side by side.
2. Description of Related Art
A conventional lens joint structure for frameless spectacles, particularly a temple-to-lens joint for connecting a temple to the outer edge of each lens and a bridge-to-lens joint for connecting a bridge to the inner edge of each lens are shown in FIGS. 16 and 17.
An abutting piece "b" is curved to fit on a selected part of the lens circumference "a", and is soldered to a joint body "c". Also, the abutting piece "b" is soldered to a joint piece "e", which has a through hole "d" at its end. The temple-to-lens joint or bridge-to-lens joint thus made by soldering is attached to the lens by applying the abutting piece "b" to the selected part of the lens circumference "a"; putting the through hole "d" of the joint piece "e" in alignment with an associated through hole "f" of the lens; and by inserting a bolt or screw "g" in these through holes to be tightened by driving the thread "h" of the screw "g" in an associated nut "i" on the other side of the lens.
As may be understood from the above, the conventional lens joint structure has a plurality of small pieces soldered, and therefore, a corresponding number of soldering steps are required in producing lens joints. This is a cause for lowering the productivity of frameless spectacles. Also, there is a fear that soldered parts of frameless spectacles are damaged or separated when the temples are inadvertently opened too wide.
In adjusting the degree at which the temples are opened with respect to the lenses, the joints are subjected to controlled bending, which, however, localizes stress strong enough to cause breaks or cracks in such localized parts of the lens.